Telephone system



July 28, 1936. H. w. ULRICH TELEPHONE SYSTEM Filec i Marbh 9, 1955 3 Sheets-Sheet l INVENTOR HW. ULRICH A TTORNE July 28, 1936.

Filed March 9, 1955 H-. W'. ULRICH TELEPHONE SYSTEM 3 Sheets-Sheet 2 FIG. 2

T -allHr m E g Q g 1 T g g INVENTOR H.W.UL R/CH A TTORNEY July 28, 1936. H. w. ULRICH TELEPHONE SYSTEM Filed March 9, 1955 3 Sheets-Sheet 3 //v l EN TOR H. W UL RICH A TTORNE V Patented July 28, 1936 UNITED STATES PATENT OFFICE TELEPHONE S YSTEM Application March 9, 1935, Serial No. 10,230

9 Claims.

This invention relates to telephone systems and particularly to those of the manual type in which operators cord circuits are used for establishing telephone connections.

1 The object of the invention is to simplify and improve manual telephone systems in which the subscribers lines are available to a number of operators, any one of which may ofi'er to serve in the establishment of a connection.

10 It has b een the practice heretofore to allow several operators who may be idle at the time to answer a calling subscribers line signal. In such arrangements the first'operator to insert her cord in the subscribers line jack proceeds to accept 15 the-called number and set up the desired connection, and any operator who answers subsequently withdraws as soon as she finds she has been preceded by another operator. The act of answering the call causes battery supply to be connected to the operators cord circuit for talking purposes h'ether she is the first or a subsequent operator to respond.

According to the present invention, an alternative to these prior systems is provided in which 25 the first operators cord to be connected to a line is supplied with current that flows over the line to enable the subscriber and operator to converse, whereas any'other cord subsequently connected to said line, while telephonically connected 30, thereto-so that the operator manipulating such second cord can both listen and speak to the subscriber, is not supplied with battery current.

Hence the insertion and Withdrawal of a second cord does not alter the flow of current in the 35 connection between the subscribers line and the first operators cord.

A feature of the invention is a cord circuit having two relays, one of which operates in any case to connect the operators telephone set to 40 the cord when a line is answered and the other of which operates to supply current to-the cord only'in case no other operator has previously connected to the line.

Another feature isv an arrangement in a system of this character in which any operator, other than the first operator to answer the call, re-" ceives a warning tone. 7

Another feature isa system of the character described in which only the first operator to answer a. call receives atone to advise her of the factv that shelis first and may proceed to accept the call. V

The foregoing and other features of the in- 55 vention will be described more fully in detail in the following specification and also in the appended claims.

The invention is illustrated in the accompanying drawings in which:

Fig; 1 shows a calling station A and a called station B, one of a plurality of connecting or cord circuits C at an operators position which may be used to interconnect such stations, and the operators telephone set and position equipment 0 common'to the cord circuits. In this figure the 10 operator's telephone circuit is arranged to give no indication to either operator or to give an indication to the second operator answering the call that the call has been answered.

. Fig. .2 shows the line circuits associated with the calling station A and called station B, one of a plurality of connecting or cord circuits 0-4 at a second position, and the operator's telephone set and position equipment 0--l Fig. 3 shows an alternative arrangement of the operators telephone circuit 0 which is used when an indication is given to the operator who has first answered the call.

Fig. 4 shows diagrammatically an unbalanced Wheatstone bridge circuit in which the controlling relays of the testing circuit are connected when a second cord circuit is connected with a line with which another cord circuit is already connected.

Each of the stations A and B is shown terminating at the central oifice in a plurality oi. answering jacks. Each answering jack has a signaling device such as a lamp associated therewith. The answering jacks and their associated line lamps for a station terminate at different operators positions.

It is to be understood that the invention is not limited to the use of the particular apparatus shown in the drawings as the apparatus and the circuit may be changed or modified in order to 40 perform the desired circuit functions. Only such parts of the cord circuits and of the operators telephone circuits as are necessary to illustrate the invention have been shown.

Referring to Fig. 1, when a subscriber at substation A initiates a call, the receiver is removed from the switchhook and a circuit is established for energizing the line relay 203. Relay 203, being energized, completes a circuit extending from grounded battery through the lower front contact of relay 203 and the filaments of line lamps 209 and I09, which are located in front of different operators at the central ofiice, any one of which operators may answer the call. The lamps fzoa and I09 are illuminated, notifying all the ator, therefore, inserts the plug 38 associated oftrelay lfidtjo groundedbatteryethrough the with the cord'circuit C into jack lBl located at her position and associated with theline of the calling station A; Upon the insertion of plug, I08

into jack Hill, relay I39 will become energized in a circuit extending from ground through the; winding of the marginal cut-off relay 204, the v sleeve contact of jack I01, the sleeve contacliglof ,1

plug 508, windings of marginal relays Ill and] 12 conductor H3, upper backbontactslof relay;[ {4} lower back contact of relay H1, conductor M5,.

left back contact of relay l le,'wmamgs of polarized relays E36 and ME, through resistance'llfl i to grounded battery in the operators telephone. circuit. This circuit will be in parallel witha cir-' cuit through resistance M9. to ground on the left: front contact of relay l2! thereby,;formin'g a potentiometer:- arrangement; i The polarized-relay I 46 will not operate with thelcurrent fl'owin'g in this direction. Marginal relays 204,1 and H2 will not receive enough .currentto cause them toebecome energized; a 7 i 1 Relay 139;,however, is energized and closes a circuitfrom'ground through the front contact of relay 1395110; grounded battery. through the windingig'of relay '51 for operating relay '6 which looks 'tlrLroughits-left front contact to ground on conductor M5;- O-peningiof the left back contact of relay I [6 opens the holding circuit for the relay 1 t3llfwhiclrnow releases; Closure of theleft front contact of'relay" H61 establishes a circuit from grounde'd'batt'ery through the left-hand winding of relay)! t6. and. the left front contact :of relay lIBto conductor; H5 in multiple with-a Qcircuit established from grounded battery,- through resistanceJl-liandkthe left front contact of relay I I6 toic'onductor H5; Battery through the left-hand winding of relay H6 in parallel with resistance [Hi to. conductor I I5 increases the current flow in conductor 1 l5 vsufliciently .to iopera'te marginal relays zw, 1H 'andfll lZiover the circuit previ ously-zdes'cribedfor operation of relay'. When' cuteoff relay 204 operated,'itdisconrrected the line; relay 203 from the. calling line thereby extinguishingthe multiple line lamps Hi9 and 209.

Operatioir'of relay ;l'lilcloses a circuit from.

ground through the'upperfront contactsqof relay ll'l', lamp ltmthrough-ithe lower back contact lower 'front'contacts of relay H I; Lamp r H0 will not operate at this time since closure of the upper frontii contact ,of relay Tlil't' connects ground through the upper left-hand winding of repeating coil lfiflto the tip conductorof the cord'C and closure of the lowerinner front contacts of the relay L7H conne'cts'batterythroughthelower lefthand winding of repeating coil I60 to thie ring conductor of the' cord C thereby clos'ing a'loopcir-' cuit over the line of calling stationA and causing relay lfi' to operate and open its lower back cont'act', 1 Openingof the lower back contact of relay H'l will: o-peri the circuit" tothe start lead I I51 This will remove the holding ground fortherelay tilt in the operators' telephone circuit thereby pluglila", windings of relays H and H2,Jcon- ISI, through'the upper back contact of relay Hi3 to ground. Relay l6l will become energized inthiscircuit and connect the; operators telephone circuit through conductors I58 and I51, the upper front contact and" the lower inner front contact qfrelay IN to battery and ground over the tip and the ring, respectively, of cord circuit C.

;;Connecti-on of battery and ground to the tip and the ring of the cord'circuit C supplies talking theci'rcuit between the operators tele phone set and'the calling station A. The operator ascertairis theparty or number desired, and

findingthattheparty desiredisstation B makes a busy test through the tip conductor ofthe calling'end'of cord C in a'manner well knownto the arts jllfzthegdesirednumber is idle; the operator inserts ;the plug I66. of the calling'cord into the multiplejack-itl. This establishes a circuit from V grounded battery, through the windinglof relay M4; the sleeve c0ntaQt10fD1llg;l65,-the sleeve contact of jack,ll, conductor I12, through the windingof,relayg2l5to groundii Relay H4 having operated removes the; shunting path from aroundresistance E69,;and opens the circuit tolconductor I43 and relay ;;l 22.;Closure of the upper front contact of relay l- M places grounded battery through resistance 169-; the, windings of relays ll 2 and H l,

tothe sleeve circuitof the calling, station A. This resistance lGQzreducesth e: current drain in the sleeve;circuitzriclosure ofthe lower inner front and: the-lower middle front contactsv ofrelay H4 w-ill close three circuits; ;;the onehf'rom grounded battery,-.the winding .ofrelay I BI to groundonthe. upper backzcontactofirelay 163; the second from grounded bat-tery,-through;lamp M5 to ground on the lower-back; contact. of relay 562; the third from'grounded battery, through the winding of relay 153 ,--;.the-. lower .outer; front, contact of relay l'6;I-,-- c onductor I55 to theleft-hand armature of relay [50; Closurefof. the lower-cuter front con'-' tact ofwrelay: H4 will establisha circuit from grounded--batterygvthrough the lower back contact ofrelay 16-3; conductor 1.55, winding of relay i5!" togrOundr: Relay {Iii-,will-operateandestablish-a ci-rcuitrfromgroundthrough its right outer front contact toj grounded battery for illuminating lamp 152 which'isa'signa'l iqthe'operator to signal-the called station-B. iRelay 2"l5'having oper'-" ated opens its-back contacts andtherebydisconnects line relay 1214' from the tip; and the ring i conductors of the line of the called-,station B. j

. The. operatonnoting-that the supervisory lamp I 'l5Z;is lighted. will depress the key 159 in the common ringing-,key'circuit; which will cause the called station B to'be, signaled :in a'manner, well known; to the art; Operation of the key 159 also will-closaa circuit' from ground through the front contact of key I59, windingvof relayl5 fl to groundedbattery, thereby causing relay i 55 to} become energized arid lock to ground in a'circuit'through its right front Contact and the in nf right frontcont'act of relay lSL' Operation of relayml50 will establish a circuitfrom ground throughthe leftfront contact offrelay 59, conducto'r I56; the; lower outer" front contact of re-" t e; relay 53, the lower mid-I dlefro'nt contact of relay H4 togrounded bat} tery, thereby causing relay I63 to become "ener gized.' Closure :of the upper front'contact of I relay-I63 will'e's'tablishalocking circuit for re'- F5 5 jacks whereupon all lay I63 from ground through the: upper front contact .of relay I63, winding of relay I 63, .to grounded battery through the lower middle front contact of relayil I4. Opening of the upper back contact of relay I63 willopen the holding circuit through relay I6I which will release thereby opening its front'contacts and disconnecting the'ope'rators telephone circuit Offrom the' cord circuit C. Opening of the lower backcontact of relay 1163 will open the holding circuitthrough conductor I55 to the winding 'ofrelayv I5I, Which will now release. Releasing of relay I5 l will open the locking circuitthrough the winding of relay I56 and the circuit through supervisory lamp I52. Relay I56 will: release and lamp I 52' will 'be extinguished, ltelease of relay I56 will remove the ground from conductor I56 and the operating circuit previously described forthe relay I63 leaving relay I63 locked to ground .through its upper front contact.

When the called station responds, supervisory relay l62 operates ina circuitestablished from gj'rounoled'battery, lower right-hand winding of repeating coil I66,-'winding of relay I62, ring .contact of plug ;I6 6,,ring contact of jack I61, subscriber. loop, tip contact of jack I61, tip cons'ubscriber'at called station B may now converse with each other and, upon completion of the conversation and restoration of their respective receivers to the switchhooks, supervisory relays I64 and I62 become de-energized, causing their associated lamps H6. and I65, respectively, to

light,'-indicating to thefoperator that conversa-.

tion has ceased. The operator, noting the, lighted'condition of the supervisory lamps, may with? draw plugs I68 and I66 from* their associated to normal. e I

Having des'cribedin detail theestablishment of a connection between a subscriber at station Ajanda subscriber at station 13, it will now be assumed 'thattheoperator at position 0 (see Fig. 1) has answered a. call from the subscriber at station A and that an operator at the position O'-I (see Fig; 2) attempts to handle the call upon the illumination of lamp 209. It is to e understood that the operator at such a position attempts to handle an incoming call immediately after the first operator has answered a call,

otherwise lamp 269 would have been extinguished upon the insertion of plug I66 into jack I61.

Indication to second operator "The second operators cord and the associated test and operators circuits shown in Fig. 2 are identical with the ones shown in Fig. 1

for the first operator. Assume thatstraps I42 and 242 on Fig. 1 and Fig. 2, respectively, are not connected to the terminals on the connecting blocks I44 and 244, and the circuit will function in the'following manner to 'give the sec 0nd operator an indication that the call has been answered. The second operator inserts the plug of the apparatus is restored inal cord irltojack I61 by the first operator. The

potentialon the sleeve of jack 261 has been provided fromithe battery associated with the sleeve of the plug I08 of the cord of the first operator. Upon theinsertion of plug 268 of the second cord circuit into jack 261, a circuit is established over-a path extending from sleeve of jack 201, sleeve of plug 268, winding of relay 2| I, winding of relay2l2, conductor 2I3, upper back contaste of relay 2I4, lower back contactof relay 2, conductor 2I5,'aleft back contact of relay 2I6, winding of relay'236, winding of relay 246,

to the potentiometer circuit including resistances.

2 I8 and 2I9. .Due to the fact that a plug'at an-' other operators position has been inserted pre-.

viously into a multiple of the jack 261, current now flows through the polarized relays 2,30 and 266 in a direction opposite to that in which it flowed throughrelays. I36 and I46 at position 0 of the first operator to answer, and is in such a. direction as to cause theoperation of polarized relay 266 only. Polarized relay. .236 willnot, ope-1,

erate because of reversed, polarity of the:current. Marginal relays 2H and 2I2-willnot operate because there is insufficient currentthrough the windings. Thereason that the current flows in a reversed direction atthistime is-dueito the fact that an unbalanced Wheatstoneybridge arrangement is formed :as shown in Fig. 4 in which the sleeve circuitofthefirst connected cord cir-. cuit'and resistance2l8 associatedgwith the second connected cord circuit form two adjacent arms with battery connected betweenthem; and

resistance 2I9, of the second connected cord cir-.- wit and cut-011 relay 264 form. the two other adjacent arms with ground connected between them; and in which relays236, 246, 2H and 2I2 of the'second connected cord circuit form the bridge or galvanometer arm. I It has been found that with suitable values of resistance this current reversal exists not only when a second op erator plugs .into the jack of a calling line but alsowhen a plurality of operators plug into the multiple jacks of acalling line after the first operator has obtained the connection. 1; 1 The operation of polarized relay 246 associated with the second connected cord circuit closes a circuitfrom ground, through the front contact of relay 246, winding of relay 225, the lower back contact of relay. 224 to grounded battery thereby causingrelay 225 to become energized. Opening of the back contacts of relay 225 will disconnect theoperators; telephone set from the cord circuittemporarily. Operation-of relay 225 will establish also a circuit from ground through the upper inner front contact of relay 225, the operators telephone'set, and the lower front contact of relay v225 to a tone lead 226, thus giving the operator a tone indicating that the call has already been answered by another operator. Operation of the, relay 225 will close a circuit also from ground through the upper outer front contact ofrelay 225, winding of slow operating relay 224. to grounded battery. (Relay 224 will become energized-and look through its lower front contact to ground on the front contact of relay 246. Opening of the lower back contact of relay 224 will diScOnnectthe grounded battery from the energizing circuit of relay 225 thereby permitting.

the release of relay225 ,and"disconnecting the tone from the operators telephone set so that the operator has received tone for only a short duration of time. Release of relay 225 'will reconnect the operators telephone circuit to conductors 251 and 258.0f, the cord circuit. Closure.

of relay-2M to ground on the upper back contact of relay 203.. Relay 26L being energized closes =s'criber at itsuppei' front contact and its lower inner front contact thereby connecting conductors258 and 251 tothe tip and the ring of cord circuit C--I.

Marginal relay 2II will not operate under this marginal condition and battery and ground will not -be connected to' the tip and ring of this cord' circuits 7 V I I i r 1 No indicationto either operator Incase it is not'desired to have an indication furnished to either the firstor the second operator answering a call, the operators telephone. circuitsO and O'-I' of Figs. land 2 are arranged in the following manner; In Fig. 1, the strap M2 is connected to theterminal block I4fll. at the pointsindicated and 'conductors I53 and I54 are disconnected from the" terminal block I44. In Fig. 2, the strap 242 is connected to the'terminal block 244 at the points'indic'ated and conductors 253 and 254 are'disconnected from terminaiiblock It will now be assumed' that: the operator at position 0 has: answered a 'call from the"sub'- station A and that the operator at the position 0I attempts to'handle the call upon the illumination of lamp 209. In operation, the telephone and cord circuits of the first operator to'a'ns'wer thecall function in the manner described heretofore It is to be understood that the operatoratposition O -I attempts 'to' handle the incoming call immediately after the first operator has'answered" the call, otherwise lamp 209 would have'been'extinguished upon the insertion of plug I08 into j ack" I01.

The second operator inserts the plug 208 -of her cord circuit into jack 201 'rhe'sieev ofja'ck" 201, being-multipled with that or jam; I01, new has a busy potentialthereon owing to thein s'ertionof plug I08 of the original cord into jack It)? "by the first operator. The'potential on the sleeve" of jack- 201 has been provided fr'om the" battery associated i with leeve of theplug I 08 or the cord or the first operator." Upon the n:

into jack 20'I,'a circuit'is established through the windings ofreIays' 230' and 240 over a path identical with thatoutlinedheretcfore whentlie sec" end operator receives an" indication.'- Relay 230' will not operate andrelay 2'40 will operate as outlined heretofore. *The operation'of polarized relay 240 associatedwith the. second connected cord circuit closes 'a' circuit fromground, through the front contact of relay 24 0, strap 242 on'ter- 'minal .block 244; resistance" 24 r, resistance 2 m to grounded battery. This will increase the current fl w through the windings 'or' maiginal' relays 2I'I and-2l'2"ca'usin g relay 2l-2 to becomeenei g'ized.- Marginalirelay 2| I will not'operate under this-marginal condition. in Operation of relay 2I2 aci -18:;

Indic'dtidw to first operator. 7

In case it i'sd'esired, to havean' indication furnishedto the first operator who' answers a..9a11, the operator's telephone circuit shown inIFig..13 should; replace the operators telephone circuits Oand'O I' onFigsl and. 2.

Referring to Fig. 3 in which the numerical designations correspond with similar designations shown'in' Fig. LWh'en a subscriber at substation Ainitiates a call,.the receiver. is removed. from the switchhook and a circuit is established for energizing the line relay. 203.. Relay, 203- being energized, completes 'a circuit extending from grounded battery through. the lower front conta t of may 203 and the filaments'of line lamps 209. and I09,which are. lac-steam front er" ,difier exit operators at" the central ofiice, any one of V which operators. answer the call-- The lamps .209 and I09 areilluminatednotifying' all the operators that a, call awaiting attention. t

It will be assumed; that at, this time the. operat r apthe' position at which lamp I .09 is 10- cated' isjfree to handle theincoming' call. This operator, therefore, ins'r'ts the plug I08 associated with the cord circuit C into jack I01 .located at her position and associated with the'line of thecalling'stationA. Upon the in'sertion o'f plug I08 into jack 'I0l., relay I will become energized' in a circuit. extending; from ground through the winding. of the marginal cut-01f.

relay 204,-the sleeve contact: of jack I01, the sleeve contact of plug I08, windings of marginal relays III and I I2; conductor I laupp'er' back contacts of relay I lower bacl; contact of'relay I I I, con-' due-tor II5.,'l er-t back contact of relay IIB, wind-..

ingsof polarized relays-Bland -I40,' through resistance [$8 to grounded; battery in the operators telephone circuit. This, circuit will be in a parallel circuitrwith' resistance I I9 to ground on the left front contact of. relay I2 [thereby forming-apotentiometer arrangement. .The polar v izedrel'ay I40 will not operate with the current flowing'in this direction Marginal relays 204, III and H2 will not receive" enough current to cause them tobe'co'me energized. i

Relay I30,beingenergized, closes circuits from ground through the. front contact of relay I30 to grounded battery through the winding of relay H6 and to grounded battery through the winding of relay l20for operatin'g relays IIS and I20.

Opening of the back contactsiof rela y. I20 will disconnect the operator's telephone set from 0011-,

ductors I5! and I58 of the cord circuit temporarily. l Closure of the front contacts of relay I20 will connect the-operator's telephone set to ground and a source of tone overconductor I26,

Opening of. theleft back contact of relay II6 opens the holdin g circuit for the relay I30 which now releases, and permits the-release of relay I20. Release of relay"l2'0'disconnects the tone or indication from the operator and reconnects the operators telephone set toflconductors I51 and I58. Closure of theleft front contact of l e-- lay H6 establishes acircuit from grounded'battery through the lefthand winding of relay I I 6 and the left front contact of relay IIB to con ductor H5 in multiple with a circuit established from ground-ed battery, through resistance Ill and the'leftfront contact of relay H0; to con ductor M5; Battery through the left-hand wind-,

ing of relay '6 in parallel with resistance In to conductor H5 increases-the current flow inconductor I15 sufficiently to operate marginal relays 204, III and I I2 over? the circuit 'pr'eviouslyi-dee lays 204, Ill and I I2 havingopera'te'd, cause the circuit to function in the manner outlined heretofore in the detailed description of the operation of the circuit shown in Fig. 1. The operator will then complete the call in the manner outline' heretofore-in'the description: of Fig. 1.

Should the second operator insert the plug 208 of her cord circuit into jack 201 after the first operator has answered, the second operators telephone circuit and cord circuit will function in the same manner as outlined heretofore in the case where no indication is given to either operator.

What is claimed is:

1. In a telephone system, a line, a plurality of connecting circuits for making connection with said line, a source of current and means for connecting the same to any one of said circuits for supplying current thereover to said line, a telephone associated with one of said connecting circuits, and means for establishing a telephonic connection between said telephone and said line by way of the associated connecting circuit without connecting said source to such connecting circuit.

2. In a telephone system, a line, a plurality of connecting circuits for making connection with said line, a source of current, means operable in response to the connection of one of said circuits to the line for connecting said source to such circuit to supply current to said line, means also responsive to the connection of a connecting circuit to the line for establishing a telephonic connection between such connecting circuit and the line, and means for establishing a telephonic connection between one of said connecting circuits and said line without connecting said source of current to such connecting circuit.

3. In a telephone system, a line having multiple terminals, a plurality of cord circuits for making connections to said terminals, a source of current, means responsive to the connection of one of said cord circuits with one of said terminals for establishing a direct current path from said source to said line, means for establishing a telephonic connection between said connected cord circuit and said line, and means responsive to the connection of a second cord circuit to one of said terminals for establishing-a telephonic connection between such second cord circuit and said line without establishing a circuit for the flow of current from said source to said second cord circuit.

4. In a telephone system, a telephone line having a plurality of terminals, a plurality of cord circuits for making connection to said line through said terminals, a telephone associated with each of said cord circuits, a source of current, means responsive to the connection of one of said cords to said line for telephonically connecting the telephone associated with such cord to the line and for connecting said source of current to the cord to supply current to said line, and means responsive to the subsequent connection of another of said cords to said line for telephonically connecting the associated telephone to said line without connecting said source to such cord.

5. In a telephone system, a subscribers line having multiple jacks, operators positions each having a telephone set, cord circuits for said positions for making connection with said line through said jacks, a source of current, relay means for automatically connecting an operators telephone set in telephonic relation to one of her cord circuits and said-line in response to the insertion of such cord in one of the jacks of said line, means also responsive to the con- -nection of a cord circuit to said line for'connecting. said source to the cord to supply current thereto and to the subscribers line, and relay means for automatically connecting another operators telephone set in telephonic relation to one of her cord circuits and said subscribers line in response to the insertion of such cord in one of the jacks of said line without connecting said source of current to said last mentioned cord circuit.

6. In a telephone system, a line, cord circuits for making connection with said line, each of said cords having two relays associated therewith, a circuit completed by the connection of one of said cord circuits to said line for operating both of the associated relays, a source of current, a circuit completed by the connections or" another of said cords to said line for operating only one of the relays associated with said last mentioned cord, means controlled by one of the relays of any cord for supplying current from said source to the line, and means controlled by the other relay of any cord for establishing a telephone connection between the cord and the line.

'7. In a telephone system, a subscribers line, a plurality of cord circuits for making connection with said line, a telephone set for each of said cord circuits, means responsive to the connection of one of said cords to said line for telephonically establishing a telephone connection between said telephone set and said line by the way of said cords, a source of current, means also responsive to the connection of a cord circuit to said line for completing a direct current path for the flow of current from said source over said connected cord circuit to the subscriber's ine, means responsive to the subsequent connection of another one of said cord circuits to said line for establishing a telephone connection between the associated telephone set and said line without completing a path for the flow of current from said source to said last mentioned cord circuit, and means to produce a tone in the telephone set associated with any cord that is connected to the line subsequent to any other of said cords.

8. In a telephone system, a subscribers line, operators positions, cords for each of said positions, a telephone set at each position, a tone mechanism for each of said positions, each of said cord circuits having two relays therein, a circuit completed by the connection of one of said cords to said line for operating both of the associated relays, means responsive to the subsequent connection of another of said cords to the line for rendering the tone mechanism at the associated operators position effective to give the operator a tone, means controlled by said tone mechanism for operating only one of the relays in the subsequently connected cord circuit, a source of current, means controlled by one of the relays of any cord for supplying current from said source to the line, and means controlled by the other relay of any cord for establishing a telephone connection between the associated operators telephone set and the line.

9. In a telephone system, a subscribers line, a plurality of cord circuits for connecting to said line, a telephone set associated with each of said cord circuits, a source of current, means responsive to the connection of one of said cord of. said cord circuit and for connecting said source of current to the cord tosupply current to said. line, means responsive to the subsequent "connection of another of said cords to said line .for establishing a telephone connection between circuits to said. line :for telephoni'callyconnecting "the associated telephone set 'to ,saitd'line by way the associat d t ienhane :set and said inetby way ;of said last mentioned cord "without connecting said source ofucurrent to such cord, and; means f r'producin a tone. in the telephone associated with any cord connected 11.0 said. line provided no, 5 -.other, cordis already connected to said line.

1 HORACE ULRICIL; 

